The present invention relates to threaded elements in particular screws and screwdrivers therefor.
Screws have been designed with various types of slot formations in the head portions thereof for engagement with the bit end of a screw driver for turning movement of the screw inward or outward relative to a cooperating element which itself may be threaded. Thus, screws have been provided in their head portions with diametral slots, the bottom depth defining walls of which lie in a common plane transverse to the axis of the screw.
Head portions of screws have also been formed with at least two diametral angularly related slots which intersect one another, the bottom depth defining walls of these slots also lying in a plane perpendicular to the screw axis. Whether one diametral or two diametral angularly related slots are provided in the head portion of the screw, in the tightening, and conversely loosening, of the screw with a screwdriver, torque applied with the screwdriver is essentially at the facing side walls, which together with the bottom wall define the slot. To obtain greater transmission of the driving torque from the driver bit to the screw, the surface area of contact between the driver bit and the side walls of the slot must be maximized.